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  • Optimization of extraction methods for the analysis of PFOA and PFOS in the salty matrices during the wastewater treatment
    Microchem. J. (IF 3.206) Pub Date : 2020-01-25
    Yang Liu; Jia Bao; Xiao-Min Hu; Gui-Lin Lu; Wen-Jing Yu; Zhen-Hao Meng

    Water bodies of numerous countries and regions in the world have been contaminated to various extents with the widespread production and usage of perfluoroalkyl substances (PFASs). Both domestic and industrial wastewaters become one of the important sources for the PFAS contaminations in natural water bodies, due to the incomplete treatment. Usually, the artificial wastewaters are complex and have high concentrations of inorganic salts, which could result in the matrix effects during the process of analysis for PFASs, contributing to quantify the target compounds inaccurately. In order to monitor the concentrations of PFAS contaminants precisely, suitable extraction methods were compared focusing on the matrix effects and characters of green analytical chemistry during the detection of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) existing with several common inorganic salts in wastewaters. The results showed that the analytical values of PFOA and PFOS were 2.8-3.6 times and 3.0-5.2 times higher than the theoretical values, respectively. The liquid-liquid extraction (LLE) and solid phase extraction (SPE) methods were used to reduce the matrix effects originated from inorganic salts, consequently the SPE method was confirmed as the optimal extraction method, based upon both the recoveries and green procedures. Combined with the application of the best parameters in real industrial wastewaters, indicating the present study would provide an accurate and green quantitative analysis of PFASs in salty wastewaters.

    更新日期:2020-01-26
  • UPLC Separation of forced degradation and process related impurities of Velpatasvir and structure elucidation by online LC-Quadrupole-Time of flight-Tandem mass Spectrometry
    Microchem. J. (IF 3.206) Pub Date : 2020-01-25
    Debasish Swain; Amrej Singh Yadav; Chandrasekhar Sasapu; Venkatakrishna Akula; Gananadhamu Samanthula

    Drug substances undergo degradation during manufacturing process and storage of finished pharmaceutical products which often results in the generation of degradation products. When process-related substances and degradation products are present as impurities, the therapeutic effect of the drug may alter or cause adverse effects. To address these issues, a mass compatible selective reverse phase UPLC method was developed and validated for separation of Velpatasvir (VPR) and some of its impurities. VPR was subjected to hydrolytic, oxidative, photolytic and thermal stress conditions as prescribed by ICH. Four process-related substances and eight stress degradation products (DPs) were separated on an Acquity Phenyl-Hexyl (100 × 2.1 mm x 1.8 µm) column using 0.1% formic acid and methanol as eluent with gradient program. The same method was applied to LC coupled tandem mass spectrometer for separation and structure elucidation of impurities. Out of eight degradation impurities; two degradation products (V1 and V2) were obtained in acid hydrolysis, another two DPs (V3 and V4) formed in alkaline hydrolysis. Four DPs (V5, V6, V7 and V8) were obtained in oxidative stress. V7 and V8 were obtained as major degradation products and their chemical structures were further confirmed by NMR experiments. The performance of this method was validated for parameters by following ICH Q2 (R1) guideline. This method can be utilized in the identification of impurities in bulk drug manufacturing and dosage form design studies.

    更新日期:2020-01-26
  • HPLC-DAD method for the quantitative determination of short-chain fatty acids in meconium samples
    Microchem. J. (IF 3.206) Pub Date : 2020-01-25
    Justyna Dobrowolska-Iwanek; Ryszard Lauterbach; Hubert Huras; Paweł Paśko; Ewelina Prochownik; Michał Woźniakiewicz; Sabina Chrząszcz; Paweł Zagrodzki

    The purpose of this study was to develop and validate a high-performance liquid chromatography with a diode-array detector (HPLC-DAD) method for the determination of short-chain fatty acids (SCFAs) such as: acetic, propionic, butyric, valeric and isovaleric acids in meconium. Additionally, the proposed analytical procedure was used to determine SCFAs in meconium obtained from 17 neonates. All determined organic acids in meconium samples were separated with good resolution. The HPLC system was characterized by high precision (the coefficient of variance ≤ 2.5%), high determination coefficients of calibration curves (R2>0.997) and low limits of detection (LOD) and quantification (LOQ). For all investigated organic acids, LOD ranged from 0.01 to 0.80 mmol/ kg and LOQ values ranged between 0.04 and 2.64 mmol/ kg. Recovery of the HPLC assay for individual analytes comprised the range of 90±2 - 106±2%. Concentrations of acids in meconium collected from healthy children varied in wide ranges (CV within the range 0.79-2.47%) and no regularity was found in the molar ratios of the individual acids. The validation parameters obtained in this study, made the HPLC-DAD method reliable and useful tool for the determination of short-chain fatty acids in meconium samples.

    更新日期:2020-01-26
  • A new naphthopyran-based chemodosimeter with aggregation-induced emission: selective dual-channel detection of cyanide ion in aqueous medium and test strips
    Microchem. J. (IF 3.206) Pub Date : 2020-01-25
    Zhen Ming Dong; Hong Ren; Jia Na Wang; Yu Wang

    A novel green emissive AIE active probe, a naphthopyran-malononitrile conjugate (NPM), was utilized for selective dual channel (colorimetric and fluorimetric) sensing of CN− ions in DMSO-water (2/3, v/v, pH=7.4) solution. The nucleophilic addition of CN− ion on the dicyano-vinyl group breaks the π-electron conjugation, thereby restricting intra-molecular charge transfer(ICT) process in the probe NPM and leading to a visual color change and observable spectral changes. NPM shows good selectivity for CN− ions with the LOD of 4.27 × 10−7 M, which renders it a candidate probe for cyanide detection in aqueous environments. For the practical applicability, NPM-coated paper strips were prepared for convenient, on-site detection of cyanide in aqueous medium.

    更新日期:2020-01-26
  • Fused-silica capillary internally modified with nanostructured octadecyl silica for dynamic in-tube solid-phase microextraction of polycyclic aromatic hydrocarbons from aqueous media
    Microchem. J. (IF 3.206) Pub Date : 2020-01-25
    Fardin Harati; Alireza Ghiasvand; Kolsoum Dalvand; Paul R. Haddad

    The internal surface of a fused-silica capillary was made much more porous, more adsorptive and resistant to chemical and mechanical stresses by chemical coating using nanostructured octadecyl silica particles. The modification process was conducted using a simple and green nucleosynthesis procedure. The internally modified capillary was used as an in-tube solid-phase microextraction (IT-SPME) device for the extraction and preconcentration of ultratrace levels of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples, followed by determination using gas chromatography-flame ionization detection (GC-FID) system. Morphology and structure of the sorbent was characterized by FT-IR, SEM and energy dispersive X-ray techniques. The effects of a range of experimental variables on the efficiency of the IT-SPME-GC-FID method were evaluated and optimized. Under the optimal conditions, good linearity (R2>0.99) was obtained for the calibration graphs over the range of 1-4000 ng mL−1. Detection limits were 0.22-0.47 ng mL−1 and relative standard deviations were obtained in the range 4.4-10.3%. Recoveries of the spiked samples were found to be 78.7-103.5%. The proposed IT-SPME-GC-FID strategy was applied successfully for the analysis of PAHs in real water samples. The results demonstrated good analytical performances, compared with those reported elsewhere for the sampling and quantification of PAHs in aqueous media.

    更新日期:2020-01-26
  • Mapping pigments and binders in 15th century Gothic works of art using a combination of visible and near infrared hyperspectral imaging
    Microchem. J. (IF 3.206) Pub Date : 2020-01-25
    L. de Viguerie; N. Oriols Pladevall; H. Lotz; V. Freni; N. Fauquet; M. Mestre; P. Walter; M. Verdaguer

    Visible and near infrared hyperspectral imaging have allowed unprecedented analyses of two major works of art of the National Museum of Catalan Art (MNAC), 15th century Gothic altarpieces: (1) Madonna of the ‘Consellers’ (Lluís Dalmau, 1443-1445) [1], an impressive piece of Catalan painting, inspired by J. van Eyck and (2) Princess Eudoxia exorcised in front of St. Stephen's tomb (Vergós Group, 1495-1500) part of the altarpiece of Sant Esteve de Granollers. Visible and near infrared (VNIR) hyperspectral imaging was used to highlight the artist's handling of materials in achieving light and shadow effects in the red draperies. The refinement in the modelling could be observed thanks to the distribution images of the red pigments. Short-wavelength infrared (SWIR) hyperspectral imaging revealed blackened azurite on visually altered areas of the two paintings. It is possible to map the presence of azurite below the altered layer and obtain a better understanding of the earlier appearance of the paintings. It was moreover possible to identify and map the binders used in both works of art: the use of oil in Dalmau's painting, as the earliest Catalan oil painting, is confirmed here whereas in the Vergós's painting both egg and oil may have been used in separate areas.

    更新日期:2020-01-26
  • Preparation of nickel-aluminum hydrotalcite nanosheet-coated carbon nanofibers and their application in the detection of salidroside
    Microchem. J. (IF 3.206) Pub Date : 2020-01-25
    Xiaojing SI; Chaolin WANG; Li LI; Daixin YE; Youli WEI; Yaping DING

    A facile and highly sensitive electrochemical sensor for salidroside was fabricated based on multilayer ultrathin films (UTFs) containing Ni–Al layered double hydroxide (LDH) and carbon fibers that obtained by electrospinning technology. The X-ray diffraction )XRD(, scanning electron microscope )SEM( and transmission electron microscopy (TEM) images show that the film surface is synthesized successfully. In addition, we constructed the electrochemical sensor using the composite nanomaterials we prepared to achieve detection of salidroside and this sensor showed a good linear range (0.2-120 μM) and a low detection limit (0.067 μM). It has also been successfully applied to the detection of actual samples, compared with HPLC method, satisfactory recovery rates have also been obtained.

    更新日期:2020-01-26
  • Zinc ferrite as a magnetic sorbent for the dispersive micro solid-phase extraction of sulfonamides and their determination by HPLC
    Microchem. J. (IF 3.206) Pub Date : 2020-01-24
    Theodoros Chatzimitakos; Constantine Stalikas

    Although zinc is known to have a high affinity for sulfonamides, there are no sample preparation procedures based on this property. In this study, the use of zinc ferrites in a magnetic, ultrasound-assisted dispersive micro solid-phase procedure for the determination of sulfonamides is developed. Zinc ferrites can efficiently and selectively extract sulfonamides from environmental and food matrixes. The synthesis of zinc ferrites is straightforward, and the resulting materials exhibit favorable magnetic properties for their harvesting after extraction. As a proof of concept, an analytical method was developed for the determination of sulfonamides in lake water and egg using high-performance liquid chromatography. The new procedure exhibits low limits of quantification (0.06 up to 0.11 μg L−1), low matrix effect (from -8% to 8%), acceptable recoveries (88-101%) and satisfactory enrichment factors (111-141). Moreover, the method has a wide linear range (up to 250 μg L−1) making it possible the determination of sulfonamides at concentrations above or below the maximum residue limit. Due to the aforementioned merits as well as the simplicity, the few synthetic steps required and the efficiency of sample preparation, the developed method can be used for routine analysis of sulfonamides. Moreover, this study highlights the affinity of zinc for sulfonamides, a property that has never reaped before in analytical chemistry.

    更新日期:2020-01-24
  • Chemistry of Modern Paint Media: the Strained and Collapsed Painting by Alexis Harding
    Microchem. J. (IF 3.206) Pub Date : 2020-01-22
    J. La Nasa; L. Nodari; F. Nardella; F. Sabatini; I. Degano; F. Modugno; S. Legnaioli; B. Campanella; M.K. Tufano; M. Zuena; P. Tomasin

    The paint media used by contemporary artists include a wide range of formulation of industrially produced paints based on synthetic resins and natural oils. We investigated the paint media used by the British artist Alexis Harding (born in 1973) in the painting “Quartet” (2003). The artwork exemplifies the artist's technique of mixing different paint media to obtain a sliding movement of the paint over the support, raising severe conservation issues and causing long-term instability of the paint. As a basis to develop a conservation strategy for the artwork, we investigated the composition of the paint by in situ non-invasive contactless external reflection infrared spectroscopy (ER-FTIR). The combination with laboratory analytical techniques applied on micro-samples allowed the identification of the pigments and the binders. The multi-analytical approach involved micro infrared spectroscopy (µFTIR), Raman spectroscopy, X-ray fluorescence (XRF), and mass spectrometric techniques coupled to chromatography (GC/MS and HPLC-ESI-Q-ToF) and analytical pyrolysis (Py-GC/MS and EGA-MS). The results of these micro-destructive investigations showed that the causes of the gliding of the paint are due the incompatibility between different materials superimposed by the artist: a fast drying alkyd paint and a mixture of siccative and non-siccative drying oils.

    更新日期:2020-01-22
  • Feasibility studies on the uptake and bioaccessibility of pesticides, hormones and endocrine disruptive compounds in plants, and simulation of gastric and intestinal conditions
    Microchem. J. (IF 3.206) Pub Date : 2020-01-22
    Dotse Selali Chormey; Merve Fırat Ayyıldız; Sezgin Bakırdere

    Large scale productions made by industries to meet the needs of the ever growing human population has led to the contamination of environmental resources such as water, air, soil and forests. These contaminants pose health risks to humans and they are capable of entering the food chain through aquatic organisms and by the uptake in plants. This study investigated the uptake of alkylphenols, hormones, pesticides and bisphenol A by plants grown in soilless media under laboratory conditions. Green onion and lettuce were selected for this purpose due to their high water intake rate. Optimum parameters of a dispersive liquid-liquid microextraction method were applied to aqueous samples to lower detection limits for the analytes determined by gas chromatography mass spectrometry. Analysis performed on the plant media on alternate days suggested migration of the analytes into the plants and this was confirmed by results (0.59 – 6.4 μg/g) obtained for analyzed plant samples at the end of the study. The plants were then treated in simulated gastric and intestinal conditions, and the results obtained suggested degradation of the analytes with time. This is the first comprehensive study on the migration of different environmental contaminants into plants and the changes they undergo when ingested into the stomach.

    更新日期:2020-01-22
  • Mixing performance in T-shape microchannel at high flow rate for Villermaux-Dushman reaction
    Microchem. J. (IF 3.206) Pub Date : 2020-01-22
    Peng lv; Liangjing Zhang; C. Srinivasakannan; Shiwei Li; Yuan He; Kaihua Chen; Shaohua Yin

    An empirical analysis is conducted to evaluate the effect of the geometric parameters of microchannel on the mixing performance at high flow rates. The mixing performance is assessed using I−/IO3− parallel competition reaction covering the whole flow regime, and measured using segregation index (Xs) covering different lengths of outlet tube (Lout), volume of mixing chamber (Vmc) covering a wide range of Reynolds number. Results show that the channel geometric parameters have significant influence on the mixing process. The segregation index is found to increase with increase in H+ concentration and volumetric flow ratio (R), while decrease with increase in the outlet (dout) and inlet tube diameter (din). The highest mixing efficiency corresponds to highest Reynolds number, c(H+) =0.05 mol/L, R=1, din=dout=5 mm, Lout=20 cm and Vmc=0.9 cm3. Regression analysis is performed to relate the micromixing time with the influencing parameters. An optimal mixing time of 0.5 ms can be achieved in a T-shape microchannel. As compared to other forms of reactors, the optimized T-shape microchannel is identified to possess excellent mixing characteristics, which could find promising applications for high flux reaction process.

    更新日期:2020-01-22
  • Detection of trace metal ions in high-purity boric acid by online two-dimensional valve switching coupled with ion chromatography-inductively coupled plasma mass spectrometry
    Microchem. J. (IF 3.206) Pub Date : 2020-01-21
    Yanping Wang; Sichao Lou; Xin Liu; Lingfan Zhang

    In this paper, a two-dimensional valve switching technique was established to detect 10 trace metal ions in high-purity boric acid by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICPMS). The system consisted of a quantitative loop, a matrix capture column, an iminodiacetic acid cationic chelating column, an ion chromatography column, two sample valves and an inductively coupled plasma mass spectrometer. The iminodiacetic acid cationic chelating column coupled the metal ions in the sample with its carboxyl functional groups to separate them from the matrix boric acid solution, and then eluted the chelated metal ions into the ion chromatographic column and inductively coupled plasma mass spectrometer. The proposed method feasibly achieved an online, rapid and efficient detection of 10 trace ions in high-purity boric acid with the optimized experimental conditions (1.0 mol/L HNO3), such as loading solution, loading flow rate, type of eluent, concentration of the eluent, sample matrix, etc. The experimental data showed that this method had good linearity in the range of 0.01-2.0 μg/L for 10 metal ions, such as Cr, Fe, Ni, Co, V, Mn, Cu, Zn, Cd and Pb in high-purity boric acid samples, with a correlation coefficient greater than 0.998. The limit of detection (LOD, S/N=3) and the limit of quantitation (LOQ, S/N=10) were 0.001-0.023 μg/L and 0.003-0.077 μg/L, respectively. The relative standard deviation (RSD) of each element was less than 3.0% (n=6) and the spiked recoveries ranged between 83%-110%. This method could be proposed to be suitable for determination of trace metal ions in real samples.

    更新日期:2020-01-22
  • 更新日期:2020-01-22
  • Distance-based paper microfluidics; principle, technical aspects and applications
    Microchem. J. (IF 3.206) Pub Date : 2020-01-21
    Basma Alsaeed; Fotouh R. Mansour

    Distance-based paper microfluidics have been widely used in environmental and biomedical analysis due to simplicity, speed, low cost and suitability for unprivileged regions with untrained personnel. The fluid behavior in the paper microfluidics is controlled by the surface tension, the temperature, the contact angle, the viscosity of the fluid, the average pore radius of the paper, and the channel width. This review discusses the principle and the applications of distance-based paper microfluidics with emphasis on the different detection reactions. The review also summarizes the techniques used in paper microfluidics manufacturing and advantages/disadvantages of each technique. Sections about reagents-free paper microfluidics and their biomedical applications are also presented. The most challenging technical problems associated with the utilization of distance-based paper microfluidics have been discussed with proposed solutions. The review covers the state-of-the-art applications of distance-based paper microfluidics and the future trends in this area.

    更新日期:2020-01-22
  • 更新日期:2020-01-22
  • Bubble-in-drop microextraction of carbamate pesticides followed by gas chromatography-mass spectrometric analysis
    Microchem. J. (IF 3.206) Pub Date : 2020-01-21
    Kochaporn Chullasat; Zhenzhen Huang; Opas Bunkoed; Proespichaya Kanatharana; Hian Kee Lee

    Bubble-in-drop microextraction (BID) is a variation of single-drop microextraction in which an air bubble is deliberately introduced to the solvent to enhance extraction efficiency. Here, BID coupled with GC-MS was developed for the extraction, enrichment and determination of carbamate pesticides in environmental water samples. Conditions affecting BID performance including the type of extraction solvent and its volume, volume of air bubble, extraction time, stirring rate, salt concentration and sample pH were evaluated. Under the most favorable BID conditions, the method provided good linearities from 0.05 to 20.0 μg L−1 with the coefficients of determination higher than 0.99. Enrichment factors were determined to be between 536 and 1097. The limits of detection and limits of quantification were in the ranges of 0.02 to 0.04 μg L−1, and 0.05 to 0.13 μg L−1, respectively. BID-GC-MS was successfully applied to the determination of carbamate pesticides in water samples with satisfactory recoveries from 81.7% to 99.0%, and intra-day and inter-day precision (relative standard deviations of <7% and <8%, respectively).

    更新日期:2020-01-21
  • Application of statistical analyses for Lapis Lazuli stone provenance determination by XRL and XRF
    Microchem. J. (IF 3.206) Pub Date : 2020-01-18
    Miriam Saleh; Letizia Bonizzoni; Jacopo Orsilli; Sabrina Samela; Marco Gargano; Salvatore Gallo; Anna Galli

    Lapis Lazuli use stretches back more than 6,500 years; ancient civilizations of Mesopotamia, Egypt, China, Greece, and Rome treasured and prized it. Afghanistan has been the oldest source for this stone, while Chile, Canada, Russia and a few other countries have been reported as sources for raw material in more recent times; the rarity of historical mines surely represents a positive aspect for the provenance clue of artefacts. Lapis lazuli is a rock consisting mainly of lazurite, to which it owes the blue colour, calcite and pyrite. Other constituents may be present, related to the different mines. In the present work, we apply the principles of Radio-luminescence (RL) exploiting as radiation source the X-ray tube of a portable commercial X-Ray Fluorescence spectrometer; in this way, X-Ray Fluorescence spectra (XRF) can be simultaneously acquired to have a larger set of data. To highlight the instrumental experimental differences, we refer to the portable set up as X-Ray Luminescence (XRL), as suggested by recent literature. We thus looked for the possibility of applying a wieldy, low cost and non-destructive method that could fit also to precious objects, based on the join use of XRF and XRL. We performed analyses on raw Lapis Lazuli stones from five different provenances, both historical and modern, and on four sets of unknown origin carved polished stones, to test our methods on real artefacts. We focalised on a limited number of samples to concentrate on the statistical treatment of spectra obtained, so to get a synergic response of the two applied techniques. We were able to obtain a clear distinction for the different classified provenances and could speculate those of unknown samples.

    更新日期:2020-01-21
  • Evaluation of antibiotic resistance and prevalence of common Salmonella enterica serovars isolated from foodborne outbreaks
    Microchem. J. (IF 3.206) Pub Date : 2020-01-17
    Zahra Rahimi Nadi; Taghi Zahraei Salehi; Iradj Ashrafi Tamai; Abbas Rahimi foroushani; Mika Sillanpaa; Mohammad Mehdi Soltan Dallal

    Salmonella is one of the major causes of foodborne outbreaks and numerous studies have reported the presence of its serovars in foodborne outbreaks. Identification of the most prevalent serovars, common polluted food types and attention to the antibiotic resistance of its serovars, are therefore key factors in the prevention and control of salmonellosis. The aim of this study is thus isolation of the common Salmonella serovars, identification of corresponding food categories and determination of their antibiotic resistance status in the stool samples of people poisoned in foodborne outbreaks in Iran during the period 2013 to 2019. Salmonella strain was isolated with serotyping and antibiogram test on 1,425 collected stools. Among them, 83 samples (5.8%) contain salmonella strain .The most frequent serovars were S. enteritidis and S. senftenberg, respectively (26.3%, 21.3%). The highest salmonellosis incidence rates were observed in the consumption of cooked meat (64.2%) then fruits and vegetables (21.4%). According to our findings, an increase in the prevalence of Salmonella senftenberg in foodborne outbreaks with 5.3% resistance to extended spectrum cephalosporins such as ceftazidime and cefotaxime, and a decrease in cefepime sensitivity and nalidixic acid resistance could be warnings of the emergence of this serovar with increasing antibiotic resistance.

    更新日期:2020-01-21
  • Simultaneous detection of ammonia and nitrate using a modified electrode with two regions
    Microchem. J. (IF 3.206) Pub Date : 2020-01-17
    Jingyi Wang; Peng Diao

    Simultaneous detection of ammonia and nitrate has significance in the application areas of environment and industry. Conventional methods include additional steps to separate ammonia and nitrate before detection. A more convenient method is required to detect ammonia and nitrate directly in their mixture. In this work, a modified electrode with electrodeposited Pt region and Ag region was prepared to simultaneously detect ammonia and nitrate for the first time. The Pt region and Ag region were designed to selectively determine ammonia and nitrate, respectively, free of interference with each other. A nonlinear correlation between ammonia oxidation current and ammonia bulk concentration and a linear correlation between nitrate reduction current and nitrate bulk concentration were found. The simultaneous detection limits of ammonia and nitrate were 3.946 μM and 0.134 mM, respectively. The modified electrode showed good long-term stability for the simultaneous detection of ammonia and nitrate with relative standard deviations of 7.10% and 3.93%, respectively. The modified electrode exhibited good anti-interference ability toward Na+, K+, Cl− and SO42−. This work demonstrated a simple and fast approach for detecting two components in solution.

    更新日期:2020-01-21
  • A New Peptide-based Chemosensor for Selective Imaging of Copper ion and Hydrogen Sulfide in Living Cells
    Microchem. J. (IF 3.206) Pub Date : 2020-01-17
    Chaowei Hao; Yongxin Li; Baomin Fan; Guangzhi Zeng; Danni Zhang; Zhaoxiang Bian; Jiang Wu
    更新日期:2020-01-17
  • Efficient development of a magnetic molecularly imprinted polymer for selective determination of trimethoprim and sulfamethoxazole in milk
    Microchem. J. (IF 3.206) Pub Date : 2020-01-16
    Laíse Aparecida Fonseca Dinali; Hanna Leijoto de Oliveira; Leila Suleimara Teixeira; Anny Talita Maria da Silva; Kaíque A D'Oliveira; Alexandre Cuin; Keyller Bastos Borges

    A molecularly imprinted polymer was synthesized on the surface of magnetic nanoparticles for subsequent application in the extraction of trimethoprim (TMT) and sulfamethoxazole (SMX) residues in bovine milk. The magnetic polymer was suitably characterized and demonstrated high stability and optimum adsorption capacity under the conditions of analysis. MMIP was used in the preparation of milk samples by the magnetic solid phase extraction technique whose optimized parameters were: sample volume, elution solvent and its volume, amount of adsorbent, stirring time, and pH of the sample. The relative recoveries of analytes were 98.66 ± 5.59 % and 75.57 ± 0.72 % for TMT and SMX, respectively. The method developed was linear in the range of concentration of 0.05–20 µg mL−1 with correlation coefficients of 0.997 and 0.994 for TMT and SMX, respectively. It was also demonstrated satisfactory accuracy and precision, as well as adequate robustness and good drugs stability in the matrix. The method was applied satisfactorily in real milk samples contaminated with residues of these antibiotics.

    更新日期:2020-01-17
  • Engineering a label- and enzyme-free detection of HIV-DNA on a cyclic DNA self-assembling strategy using G-triplexes as the signal reporter
    Microchem. J. (IF 3.206) Pub Date : 2020-01-16
    Yunpeng Han; Rong Zou; Ling Xiang; Chunyan Chen; Changqun Cai

    An efficient amplification strategy based on the G-triplex DNA structure was developed for label- and enzyme-free fluorescence detection of human immunodeficiency virus (HIV) DNA. In this system, three hairpin molecules (H1, H2, and H3) were used to detect the target and amplify the signal. Fluorescence enhancement was achieved by producing more G-triplexes to bind with Thioflavine T. A detection limit of 33 pM with good linearity in the range from 400 pM to 110 nM was observed. This method avoided using of enzyme and cumbersome labeling procedures and was relatively superior to previous G-quadruplex-based approaches, which often encounter some difficulties in control and excitation. Moreover, the application for detecting HIV-DNA in biological fluids indicates that further applications for clinical diagnosis are expected.

    更新日期:2020-01-17
  • Multivariate optimization and validation of a new procedure for simultaneous determination of folic acid and folinic acid based on enhancement effect of n-dodecylpyridinium chloride
    Microchem. J. (IF 3.206) Pub Date : 2020-01-16
    Mahdi Mollaei; Sayed Mehdi Ghoreishi; Asma Khoobi

    The present study is a first report about of an electrochemical sensor for simultaneous determination of folic acid (FA) and calcium folinate (CF) as a cationic surfactant. Also, the work is a first successful application of n-dodecylpyridinium chloride (DPC) as a modifier in voltammetric simultaneous measurements. This study is based on the adsorption of cationic surfactants at the surface of a carbon paste electrode (CPE) to improve the electrochemical response of the tow analytes. The enhancement effect of DPC is compared with CTAB by differential pulse voltammetry (DPV) technique and DPC shows the better results as a modifier. Other novelty of the work is application of multivariate optimization for optimization of effective parameters in the voltammetric peak current of the analytes. Under the optimized conditions, a peak separation of CF and FA is higher than 270 mV. CPE in the presence of DPC shows wide linear responses for CF and FA in the concentration ranges of 0.1-100.0 µM and 0.05-10.0 µM with detection limits of 24.0 nM and 7.5 nM (3σ), respectively. CPE in the presence of DPC exhibits good repeatability and stability for the two analytes. At the last, CPE in the presence of DPC was successfully applied to the simultaneous detection of FA and CF in urine real samples.

    更新日期:2020-01-17
  • A modified sensitive carbon paste electrode for 5-fluorouracil based using a composite of praseodymium erbium tungstate
    Microchem. J. (IF 3.206) Pub Date : 2020-01-16
    Mehdi Rahimi-Nasrabadi; Farhad Ahmadi; Hana Beigizadeh; Meisam Sadeghpour Karimi; Ali Sobhani-Nasab; Yvonne Joseph; Hermann Ehrlich; Mohammad Reza Ganjali

    This paper describes the modification of a modified carbon paste electrode (CPE) using nanoparticles of praseodymium erbium tungstate (Pr:Er). The modified electrode was used for the sensitive voltammetric detection of an anticancer drug (5-fluorouracil (5-FU)) using. The modified-CPE was evaluated using cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) and the resulting data showed the irreversible 5-fluorouracil oxidation peak around 1.0 V vs. Ag/AgCl. Some key parameters such as pH, the amount of the modifier, potential amplitude, step potential and frequency were studied and optimized. The square wave voltammetry (SWV) analytical calibration curve was linear in the range of 0.01-50 μM, with a detection limit of 0.98 nM analyses. The electron transfer coefficient (α) was also determined to be 0.76. The analyte concentration was also determined in pharmaceutical formulations and recovery percentages were found to be in the range of 96–102%. The sensor had good reproducibility and repeatability with acceptable RSD values of 3.6%, and 1.02% and a rather long-term stability of around one month. The as-synthesized nanoparticles were also characterized using FESEM, TEM, FTIR and XRD techniques.

    更新日期:2020-01-17
  • Electrochemical Properties of Gold Nanosheets: Investigation of the Effect of Nanosheet Thickness Using Chemometric Methods
    Microchem. J. (IF 3.206) Pub Date : 2020-01-16
    S. Ahmadpour; M. Ajamian; J. Tashkhourian; A. Safavi; B. Hemmateenejad

    Gold nanostructures have been widely studied because of their unique size and shape dependent properties. Two-dimensional (2D) Au nanosheets (AuNSs) attract much attention for their unique features and potential applications. One parameter that should be considered in their potential applications, is their thicknesses. In this study AuNSs were synthesized in three thicknesses (25 nm, 45 nm, and 65 nm), and their electrochemical properties at a glassy carbon electrode were compared. Multivariate curve resolution-alternating least squares (MCR-ALS) was used to resolve the total current to its three main constitutes, which are faradaic, step charging and induced charging currents. The extent of contribution of each current was calculated and related to the parameters affecting the electrochemical systems such as the nature of supporting electrolyte or the composition of the electrode. The results showed that the thickness of AuNSs has a significant effect on the extent of contribution of all currents. For example, the contribution of the faradaic current is higher for 25 nm thickness of AuNSs whereas the contribution of the charging current changes reversely. Our results confirmed that thinner AuNSs are more suitable for using in construction of electrochemical sensors.

    更新日期:2020-01-17
  • A zinc mixed-ligand microporous metal-organic framework as solid-phase microextraction coating for priority polycyclic aromatic hydrocarbons from water samples
    Microchem. J. (IF 3.206) Pub Date : 2020-01-15
    Federica Bianchi; Asha Pankajakshan; Fabio Fornari; Sukhendu Mandal; Paolo Pelagatti; Alessia Bacchi; Paolo Pio Mazzeo; Maria Careri

    For the first time, a novel triple catenated Zn2+-pillared metal-organic framework (PUM 210) is proposed as solid-phase microextraction coating for the extraction of 16 priority pollutant polycyclic aromatic hydrocarbons (PAHs) from water samples and their subsequent quantitation via gas chromatography-mass spectrometry. Extraction was optimized by using a central composite face centered design followed by the multicriteria method of the desirability functions. The best conditions for the extraction of the sixteen analytes were found in correspondence to an extraction temperature of 30°C and an extraction time of 30 min. Method validation allowed to obtain quantitation limits in the 1 – 7 ng/L range, a repeatability within 16% relative standard deviation (RSD), an intermediate precision within 22% RSD at limits of quantitation, and recovery rates in the 85 (±5) – 117 (±21)% range. As for selectivity, PAHs extraction proved to be feasible also in the presence of high concentration levels of potentially competing compounds like benzene, toluene, ethylbenzene and xylenes with steric hindrance playing a key role in analyte inclusion. Enrichment factors in the 300 (±5) – 14950 (±150) range were obtained, being the heaviest compounds better extracted with respect to commercial coatings. Finally, the method was applied for the quantitation of PAHs in sixty-nine underground water samples during a monitoring campaign carried out in 2018.

    更新日期:2020-01-15
  • HPTLC-bioautography/SERS screening nifedipine adulteration in food supplement based on Ginkgo biloba
    Microchem. J. (IF 3.206) Pub Date : 2020-01-15
    Yisheng Chen; Caihong Huang; Zhengyu Jin; Xueming Xu; Yina Cai; Yuxiang Bai

    Ginkgo biloba was a popular phytomedicine as the essential ingredient of many food supplement. In this work, a bio-inspired HPTLC method was proposed for the visualized screening of nifedipine adulteration in food supplement based on Gingko biloba. To customize the visualization of the analyte by inhibiting bacterium (Photobacterium phosphoreum) bioluminescence, the silica gel plate that gives the highest detectability was selected as the stationary phase of separation. Thereafter, the HPTLC procedure (toluene and ethyl acetate 8/2, v/v, as the mobile phase, to a distance of 60 mm) was optimized and standardized as a sample cleanup tool to exclude noises caused by bioactive co-extracts. Then, the separation result fixed on the plate layer was selectively visualized as dark bands against the white background, only after 6 min exposure. To achieve quantitation of the obtained HPTLC images, an enhanced quantitative analysis was optimized via software (ImageJ) facilitated pixel scanning, offered remarkable sensitivity (LOD=24.0 μg/g), linearity (R2=0.9985 within 50-300 ng/band) and precision (RSD<7.2%). Further, the developed method was validated with real samples (recovery rates within 81.0-92.8%). In conjunction with image quantitation, in-situ surface enhance Raman spectroscopy was incorporated into the analysis, using silver nanoparticles as the active substrate and He:Ne 633 nm lamp the incident laser source. The obtained SERS spectra displayed highly characteristic fingerprint patterns, enabling unambiguous confirmation of effect-directed results.

    更新日期:2020-01-15
  • Determination of paracetamol in synthetic urea and pharmaceutical samples by shaker-assisted deep eutectic solvent microextraction and spectrophotometry
    Microchem. J. (IF 3.206) Pub Date : 2020-01-14
    Bünyamin Doğan; Adil Elik; Nail Altunay

    In the present study, a new, simple and cheap shaker-assisted deep eutectic solvent microextraction (SA-DES-ME) procedure was developed for extraction of paracetamol in synthetic urea and pharmaceutical samples prior to its determination by UV-VIS spectrophotometer. The SA-DES-ME procedure is based on the selective extraction of paracetamol which deep eutectic solvents (DESs) prepared with choline chloride (ChCI)/betaine (Bet) and different hydrogen bond donors (HBDs).The DESs was used as the extraction solvent for the separation of the paracetamol-containing complex from the sample solution. Optimum values of experimental parameters were determined by univariate optimization method. Under optimum conditions, analytical results such as good linearity (50-800 µg L−1), quantitative recoveries (94.2-107.1%), low detection limit (14.9 µg L−1), and high sensitivity enhancement factor (135) were obtained using the proposed method. Additionally, the relative standard deviations (RSDs%) were less than 3.3% for repeatability and reproducibility analysis. The proposed procedure was successfully applied to the extraction and determination of paracetamol in pharmaceutical samples and synthetic urea using standard addition.

    更新日期:2020-01-15
  • Solid-phase microextraction for the determination of iron organic compounds in seawaters and soils by gas chromatography coupled to microwave-induced plasma with atomic emission detection spectrometry
    Microchem. J. (IF 3.206) Pub Date : 2020-01-14
    Rosa Peñalver; Natalia Campillo; Ignacio López-García; Manuel Hernández-Córdoba

    A rapid solvent-free method for determining ferrocene and five derivatives (1,1´-dimethylferrocene, ferrocenecarboxaldehyde, acetylferrocene, ferroceneacetonitrile and benzoylferrocene) in seawaters and soils using direct immersion solid-phase microextraction (DI-SPME) and gas chromatography coupled to microwave-induced plasma with atomic emission detection (GC-MIP-AED) is developed. The bonded divinylbenzene/Carboxen/polydimethylsiloxane commercial fiber provided good extraction efficiency in the DI mode for all the compounds, applying a fiber time exposure of 15 min at ambient temperature. The analytes were previously isolated from the soil matrices (0.2 g) by ultrasound-assisted extraction using 7 mL of 0.1 M acetate/acetic buffer solution. The absence of a matrix effect was confirmed in the case of seawaters, which permitted calibration against aqueous standards. However, the standard additions method was required for soil analysis. Detection limits (DLs) were in the 3-110 pg mL−1 and 0.9-4 ng g−1 for seawater and soils, respectively. Analysis of the different samples using the proposed DI-SPME-GC-AED method only provided an analytical signal for ferrocene in one seawater sample at a concentration near its DL (3 pg mL−1).

    更新日期:2020-01-15
  • In situ formation of Ag/Au nanorods as a platform to design a non-aggregation colorimetric assay for uric acid detection in biological fluids
    Microchem. J. (IF 3.206) Pub Date : 2020-01-14
    Mohammad Amjadi; Tooba Hallaj; Elham Nasirloo

    Herein, we report on a sensitive probe for colorimetric detection of uric acid based on the formation of Ag shell on Au nanorods (Ag/AuNRs) in the presence of uric acid. Uric acid can reduce Ag+ to Ag atoms which deposit on the surface of AuNRs and form Ag shell. As a result of this phenomenon, the dielectric environment around AuNRs changes and the longitudinal surface plasmon resonance (SPR) peak of AuNRs blue-shifts, leading to the change of solution color from purple to green. Based on these facts, a colorimetric sensor for the detection of uric acid in the concentration range of 0.1-1.0 µM with a detection limit of 0.065 µM was developed. The method was applied for analysis of uric acid in human plasma and urine samples with satisfactory results. The sensor can be used for uric acid detection even with bare eyes.

    更新日期:2020-01-15
  • Anti-Solvatochromic Fluorescence of Thiazole [5, 4-d] thiazole by Forming Hydrogen Bond Network and Its Application in fast Detection of Trace Water
    Microchem. J. (IF 3.206) Pub Date : 2020-01-14
    Yan Liu; Zengqiang Liang; Zhaohui Li; Keran Zhao; Yuanqiang Sun; Xiaobing Zhang; Ran Yang; Lingbo Qu
    更新日期:2020-01-15
  • Quantification of live Gram-positive bacteria via employing artificial antibacterial peptide-coated magnetic spheres as isolation carriers
    Microchem. J. (IF 3.206) Pub Date : 2020-01-14
    Enci Fan; Jinxiu Peng; Yanli Shi; Hui Ouyang; Zhaoqing Xu; Zhifeng Fu

    A novel artificial antibacterial peptide was prepared by minor modification of the amino acids sequence of a natural peptide protonectin. Distinct from protonectin with natural broad-spectrum antibacterial activity, the designed peptide named as Phe11-protonectin displayed obviously improved selectivity towards Gram-positive (G+) bacteria. Adopting Phe11-protonectin as the recognition reagent, a bioluminescent method was established to quantify live G+ bacteria. Phe11-protonectin-coated magnetic spheres were employed as carriers for isolating G+ bacteria from sample matrixes. The isolated bacteria were lysed to release intracellular adenosine triphosphate, followed by bioluminescent signal collection for quantifying the amount of live G+ bacteria. Staphylococcus aureus, Streptococcus mutans and Bacillus cereus were adopted as model bacteria to explore the feasibility of this method. The linear range for G+ bacteria was 2.3 × 103 - 1.2 × 107 CFU mL−1, and the limit of detection was 2.2 × 102 CFU mL−1 (3σ). The quantification process composed of bacteria isolation, bacteria lysis and signal detection was completed within 33 min. Both Gram-negative and dead G+ bacteria displayed very minor interference to the method for quantifying live G+ bacteria. It has been successfully employed for four types of sample matrixes including peach juice, glucose injection, human urine and lake water, revealing its application prospect in food and drug safety control, clinical diagnosis and hygiene monitoring.

    更新日期:2020-01-14
  • Voltammetric measurement of Escherichia coli concentration through p-APG hydrolysis by endogenous β-galactosidase
    Microchem. J. (IF 3.206) Pub Date : 2020-01-14
    Yu-Jui Fan; Yu-Chen Hsu; Bing-Chen Gu; Chia-Che Wu

    This paper reports a facile electrochemical detection method for Escherichia coli (E. coli) that does not use DNA amplification or immunoassay. The detection principle is based on the activity of the β-galactosidase (β-gal) endogenous enzyme, which hydrolyzes p-aminophenyl-β-D-galactopyranoside (p-APG) into p-aminophenol. After E. coli consumes p-APG within 30 minutes, the remaining p-APG is oxidized on a gold electrode using cyclic voltammetry and square wave voltammetry. The β-gal expression level is increased through treatment with a β-gal expression inducer (isopropyl-β-d-thiogalactopyranoside), and the hydrolysis reaction of p-APG is facilitated through permeabilization treatment with sodium dodecyl sulfate. The calibration curve for E. coli has a working range of 102–104 colony-forming units per mL in nutrient broth buffer. The total assay time is less than 100 min. The successful application of this approach indicates the possibility of rapid detection.

    更新日期:2020-01-14
  • Beyond the visible: the Viterbo Crucifixion panel painting attributed to Michelangelo Buonarroti
    Microchem. J. (IF 3.206) Pub Date : 2020-01-13
    Claudia PELOSI; Angela LO MONACO; Mauro BERNABEI; Giorgia AGRESTI; Claudia COLANTONIO; Antonio PERRI; Daniela COMELLI; Gianluca VALENTINI; Cristian MANZONI

    The painting object of the present work, currently exposed in the Museum of Colle del Duomo in Viterbo (Italy), has been dated back by art historians to the 16th century and it owes its relevance to a still discussed attribution to Michelangelo Buonarroti. For this reason, art historians and the responsible curator of the Museum commissioned scientific investigations to support and explain their hypothesis about the painting attribution and dating. Here we report the results of two sets of investigation: diffuse reflectance hyperspectral imaging and X-ray fluorescence spectroscopy of the painting; radiocarbon dating and identification of the panel wood. The hyperspectral dataset, coupled with X-ray fluorescence spectra on selected analysis points, reveals the presence of precious ultramarine blue and vermillion pigments, confirming the importance of the painting committer. Wood analysis and radiocarbon dating by wiggle matching technique revealed that the botanical species used for the panel is Cypress (Cupressus sempervirens L.), and enabled dating the painting around AD 1500± 25, providing to art historians a further element for the attribution of the artwork.

    更新日期:2020-01-14
  • The effect of fermentation time on in vitro bioavailability of iron, zinc, and calcium of kisra bread produced from koreeb (Dactyloctenium aegyptium) seeds flour
    Microchem. J. (IF 3.206) Pub Date : 2020-01-13
    Mohamed Ismael Ahmed; Xueming Xu; Abdellatief A. Sulieman; Yang Na; Amer Ali Mahdi

    The effects of different fermentation time (0-72 h) on the composition of the anti-nutrients, phytic acid (PA), oxalic acid (OA) and tannins and on the bioavailability of iron (Fe), zinc (Zn), and calcium (Ca) of kisra bread from Koreeb (Dactyloctenium aegyptium) seeds was studied. The results of the study revealed that PA, OA, and tannins content decreased significantly (P < 0.05) whereas the amount of total Fe, Zn and Ca was increased with the fermentation time. Fifty-four hour fermentation resulted in maximum reduction of PA (26.9%), while 72 h fermentation recorded a maximum reduction of OA and tannins by 80.9 and 46.5%, respectively. The increase in fermentation time decreased the molar ratios of PA/Fe, PA/Zn, PA/Ca and OA/Ca of fermented kisra bread, therefore, fermentation enhanced the bioavailability of minerals (Fe, Zn and Ca). This fermented kisra bread could be a source of easily available minerals for individuals suffering from digestive disorders, as well as used as a functional food in general.

    更新日期:2020-01-14
  • Fluorescence quenching of photoluminescent organic polymer nanofilms by ferric ions
    Microchem. J. (IF 3.206) Pub Date : 2020-01-13
    Baoxi Feng; Zhen Xu; Chenggang Qi; Xiumei Guo; Ligang Gai
    更新日期:2020-01-13
  • Carbon dots-enhanced chemiluminescence method for the sensitive determination of iodide
    Microchem. J. (IF 3.206) Pub Date : 2020-01-13
    Yue Li; Suqin Han

    The nitrogen doped carbon dots regulated by formaldehyde were synthesized using citric acid and melamine by a simple hydrothermal method. The obtained carbon dots (MFCD) significantly enhanced the weak chemiluminescence (CL) reaction of K2Cr2O7 with NaHSO3 by means of energy transform from the intermediate of excited sulphur dioxide (SO2*) and the radiative recombination of oxidant-injected holes and electrons. Interestingly, it was discovered that iodide was effective in enhancing the CL intensity of this system. Based on this finding, the MFCD-based CL system as a sensitive and selective probe was applied for detection of nM levels of iodide ions. Under optimum conditions, the probe had a linear calibration range from 0.03 to 5.0 μM with a detection limit of 5.6 nM. The developed CL method was applied for the detection of iodide in milk and mineral water samples.

    更新日期:2020-01-13
  • nSynchrotron µ-XRF imaging and µ-XANES of black-glazed wares at the PUMA beamline: insights on technological markers for colonial productions
    Microchem. J. (IF 3.206) Pub Date : 2020-01-13
    A. Gianoncelli; S. Raneri; S. Schoeder; T. Okbinoglu; G. Barone; A. Santostefano; P. Mazzoleni

    Well-designed archaeometric studies can provide pertinent information on ancient ceramic production technologies and allow better understanding of their manufacturing methods. In this regard, fine and glazed ceramics constitute a particularly interesting class of archeological artefacts, with increasing scientific interest for their production and functional aspects. In the present work, we analyze a selection of Attic and western-Greek black-glazed vessels from two archaeological excavations in Gela (Sicily, Italy), currently held at the Gela Archaeological Museum. The goal of the present study is to shed light on the archeological questions concerning the discrimination among western-Greek colonial workshops and the possible identification of different manufacture technologies throughout the colonies. Synchrotron µ-X-Ray fluorescence (µ-XRF) imaging and µ-X-Ray absorption near edge spectroscopy (µ-XANES) were performed at the newly opened PUMA beamline of the SOLEIL synchrotron radiation facility. Using µ-XRF and µ-XANES we evaluated possible elemental variations in the glaze and their Fe-speciation, which can provide chemical and mineralogical markers for provenance identification. µ-XRF mapping of cross-sections spanning from the glaze to the body of each sample highlighted a variety of black-glaze compositions, including those characterized by high levels of Zn, which may be used as technological marker. Overall, our results provide chemically based criteria for the discrimination of Attic and western-Greek black-glazed colonial products and highlight distinguishing technological features among western-Greek workshops in Sicily and South-Italy.

    更新日期:2020-01-13
  • Thermal analysis of carbonate pigments and linseed oil to optimize CO2 extraction for radiocarbon dating of lead white paintings
    Microchem. J. (IF 3.206) Pub Date : 2020-01-13
    Cyrielle MESSAGER; Lucile BECK; Laurence DE VIGUERIE; Maguy JABER

    Lead white was a white pigment extensively used in paintings from Antiquity until the beginning of the 20th century. It is composed of hydrocerussite (Pb3(CO3)2(OH)2) and cerussite (PbCO3). Historical recipes report metallic lead, vinegar and horse manure as ingredients to produce the two lead carbonates. The incorporation of organic CO2 carrying 14C representative of the time of manufacture of lead white allows radiocarbon dating of this pigment. One possible protocol for lead white paint preparation for dating is based on the extraction of carbon from lead carbonates by thermal decomposition. Since lead white paints are mixed with a binder and other pigments, a thermogravimetric study was implemented to study the extraction of each component. The measurements were carried out on samples of modern paints prepared with lead white (lead carbonate), Meudon white (calcium carbonate) and linseed oil. The results show that it is possible to separate the carbon of interest (carrying the 14C signature: lead white and linseed oil) from the dead carbon coming from geological carbonates (containing no radiocarbon: Meudon white) by heating the paint sample at 400°C. This study provides a better understanding of the thermal behavior of these three paint constituents and confirms the validity of the thermal protocol for the preparation of lead white paints for radiocarbon dating.

    更新日期:2020-01-13
  • Application Of Thymine-Based Copolymers In The Quantification Of Organic Pollutants In Water By Sensitized Fluorescence
    Microchem. J. (IF 3.206) Pub Date : 2020-01-13
    Julieta Ledesma; Carlos E. Boschetti; Debora M. Martino; Santiago A. Bortolato

    Bio-inspired copolymers based on thymine can interact with certain organic molecules and therefore they can be used as organized media or as optical sensors for analytical determinations. Particularly, the thymine-based copolymers have a high affinity for benzo(a)pyrene (BaP) and pyrene (Pyr), two main persistent organic pollutants in water. In the present work, such interaction is applied for the development of a simple analytical method based on fluorescence enhancement of BaP and Pyr. Since BaP and Pyr fluorescence spectra are strongly overlapped, a multivariate analysis of the data is proposed. The selectivity of the method was achieved through a parallel factors analysis (PARAFAC) of excitation-emission fluorescence matrices. The method performance was tested by simultaneous determination of BaP and Pyr in water samples, without pre-concentration steps or full chromatographic resolution. Studies of recovery for both analytes added to tap and surface waters were done, obtaining results in the order of 87-115%. The analysis was performed in the presence of additional species whose signals overlap with those of the analytes. In all cases, the calculated analytical figures of merit were compared with those obtained by the reference chromatographic method. In addition, a comparison of our method with the reference one is made based on the calculation of their respective eco-scales. The quality of the achieved results indicates that a second-order advantage was reached, while our method represents a greener alternative than the reference chromatographic methodology.

    更新日期:2020-01-13
  • Copper-bismuth-film in situ electrodes for heavy metal detection
    Microchem. J. (IF 3.206) Pub Date : 2020-01-11
    Matjaž Finšgar; Laura Kovačec

    This work presents the development and validation of 8 new in situ bismuth-copper-film electrodes (BiCuFEs) for Zn(II), Cd(II), and Pb(II) trace analysis in 0.1 M acetate buffer. The BiCuFEs were compared with in situ copper-film (CuFE) electrodes – new electrodes that have recently been reported. The formation of every in situ electrode was performed at two different concentrations, i.e. 0.5 and 1.0 mg/L. All BiCuFEs were selective for Zn(II), Cd(II), and Pb(II) determination. By using different BiCuFEs, the lower limit of the linear concentration ranges for Zn(II), Cd(II), and Pb(II) was generally lower compared with those for the CuFEs. Moreover, the BiCuFEs were generally more sensitive and had lower limits of detection for Zn(II), Cd(II), and Pb(II) determination than the CuFEs. The precision of the methods and the precision of the systems were satisfactory for the vast majority of the electrodes tested (RSD < 20.0%). For selected BiCuFEs a possible interference effect on the stripping signals of the analytes was checked in the presence of Fe(II), As(III), Na(I), K(I), Ca(II), Mg(II), Sn(II), Sb(III), and NO3– in water solution. Moreover, electrochemical impedance spectroscopy measurements were performed in order to determine if the electroanalytical system is under a kinetic-controlled or mixed kinetic- and diffusion-controlled process. Furthermore, the applicability of the selected BiCuFEs was confirmed by real water sample analysis.

    更新日期:2020-01-13
  • Ultrasound assisted-dispersive-modification solid-phase extraction using task-specific ionic liquid immobilized on multiwall carbon nanotubes for speciation and determination mercury in water samples
    Microchem. J. (IF 3.206) Pub Date : 2020-01-11
    Nafiseh Esmaeili; Jamshid Rakhtshah; Eskandar Kolvari; Hamid Shirkhanloo

    An efficient method based on 1-(3-aminopropyl)-3-methylimidazolium hexafluorophosphate (TSIL) immobilized on multiwall carbon nanotubes ([email protected] [Apmim][PF6]) was used for speciation of inorganic/organic mercury (Hg2+, R-Hg or O-Hg) by ultrasound assisted-dispersive modification solid-phase extraction (UAS-DM-SPE) which was combined with cold vapor atomic absorption spectrometry (CV-AAS). The mixture of MWCNTs @ [Apmim][PF6] in acetone was injected to water samples in polypropylene syringe filters (PSF) which was already adjusted pH up to 8.5. After shaking, the Hg(II) and O-Hg were simply extracted on amine group of [Apmim][PF6] as TSIL and then, separated from the liquid phase by pushing plunger of PSF. The Hg(II) and O-Hg loaded in MWCNTs @ [Apmim][PF6] were back-extracted based on the eluent solution (HNO3, 0.5 mL, 0.2 mol L−1) with/without microwave system (UV radiation at 165°C). Finally, the concentration of mercury was determined by CV-AAS. By microwave, organic mercury species in remained solution were changed to Hg (II) and the total amount of mercury (T-Hg) was determined. Finally, O-Hg concentration was computed by subtracting the Hg (II) concentration from T-Hg. Under the optimized conditions, the linear range, LOD and enrichment factor for Hg (II) and O-Hg were achieved (0.02 – 3.6 μg L−1; 0.02 – 3.4 μg L−1), (5.2 ng L−1; 5.8 ng L−1) and (19.9; 19.7), respectively (Mean of RSD<1.91%). Also, the capacity absorption based on MWCNTs and [email protected] [Apmim][PF6] for O-Hg and Hg(II) ions were achieved 23.6/27.3 mg g−1 and 174.3/186.2 mg g−1, respectively. The proposed method validated for speciation of mercury by ICP-MS and standard reference material (SRM).

    更新日期:2020-01-13
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  • Preparation of ferrofluid from toner powder and deep eutectic solvent used in air-assisted liquid-liquid microextraction: Application in analysis of sixteen polycyclic aromatic hydrocarbons in urine and saliva samples of tobacco smokers
    Microchem. J. (IF 3.206) Pub Date : 2020-01-11
    Abolghasem Jouyban; Mir Ali Farajzadeh; Mahboob Nemati; Ali Akbar Alizadeh Nabil; Mohammad Reza Afshar Mogaddam

    A new ferrofluid prepared from toner powder and deep eutectic solvent was used in air-assisted liquid-liquid microextraction procedure for extraction of sixteen polycyclic aromatic hydrocarbons from urine and saliva samples of tobacco smokers. In this work, initially, a water-immiscible deep eutectic solvent is synthesized by mixing choline chloride and stearic acid under mild conditions and used as a support solvent in the preparation of ferrofluid from toner powder. Then, a few microliters of the prepared ferrofluid is mixed with sample solution and dispersed in all parts of the solution by performing aspirating/dispersing cycles. To collect the ferrofluid, a magnet is deposited at the outside of the tube and the solution is discarded. The analytes in the collected phase are back-extracted into n-heptane and determined by gas chromatography–mass spectrometry. The validation parameters including limit of detection and quantification, stability, accuracy, linearity, selectivity, precision, enrichment factor, and extraction recovery were studied and the data showed that the method have low limits of detection (in the range of 6-21 ng L−1 in deionized water and 18-63 ng L−1 in saliva and urine samples, respectively) and quantification (in the range of 20-72 ng L−1 in deionized water and 60-216 ng L−1 in saliva and urine samples). Extraction recoveries and enrichment factors ranged from 61-84% and 305-420, respectively. Relative standard deviations of ≤9% for the extraction of 200 ng L−1of each analyte were obtained for intra– (n = 6) and inter–day (n = 6) precisions. Finally, urine and saliva samples of tobacco smokers were successfully analyzed using the proposed method.

    更新日期:2020-01-11
  • SERS-active hydrophobic substrates fabricated by surface growth of Cu nanostructures
    Microchem. J. (IF 3.206) Pub Date : 2020-01-11
    Menekse Sakir; Erkan Yilmaz; M.Serdar Onses
    更新日期:2020-01-11
  • Optical reflectance apparatus for moisture content determination in porous media
    Microchem. J. (IF 3.206) Pub Date : 2020-01-11
    J. Melada; P. Arosio; M. Gargano; I. Veronese; S. Gallo; N. Ludwig

    Monitoring surface moisture content (MC)is a required activity and a topic of current interest in conservation studies. The present work examines the possibility of using the spectral reflectance factor at 970 nm (Rλ970) for the noninvasive quantitative determination of surface MC in building materials. Indeed, the quantification of surface liquid water by optical measurements is poorly exploited on porous media despite it is well documented in many remote sensing technologies such as in agriculture, soil science and some industrial application. The measurements apparatus is tested in a laboratory experiment on different specimens of building materials. The custom-made detector is a Si-core Avalanche Photo Diode (APD) operating in Geiger mode which satisfy the requirements of non-invasiveness and ease of use with the additional opportunity for developing economic, automated and reliable solutions. The results obtained for six representative cultural heritage building materials clearly show the dependence between Rλ970 and surface SMC: Rλ970 increases as surface MC decrease following the drying process of an unsaturated porous matrix i.e. evaporative flux supported by capillary pumping. This work reports the possibility to use the reflectance value at a specific wavelength for an alternative and non-invasive measurements of MC.

    更新日期:2020-01-11
  • Multi-analytical approach for the study of the painting palette of historic theatre sceneries
    Microchem. J. (IF 3.206) Pub Date : 2020-01-10
    Elżbieta Szmit-Naud

    Illusionist painted scenery sets illustrated all kinds of theatrical events from traditional ‘Italian stage’ history. They are a unique heritage of both theatre and painting techniques. Some of those large-scale but ephemeral objects have luckily been preserved in relatively few collections, today not yet fully examined. The aim of the presented study was to widen the scope of information on the subject of the pigment palette employed in this kind of paintings. In order to achieve it, microsamples taken from set items from seven European collections (two Czech, Swedish, Belgian, German, Norwegian and Polish) from the 18th to the 20th century were subject to examination. A multi-technique approach was applied in a successive, selective and complementary way. After initial observation, in the first step elemental (X-ray fluorescence spectroscopy) and molecular (attenuated total Reflectance Fourier -transform infrared spectroscopy) techniques were applied. Further on, microscopic images of the cross-sections of paint layers were analysed in visible light, UV–induced fluorescence and in near infrared false colour technique (NIRFC). That was followed by Scanning Electronic microscopy coupled with Energy Dispersive X–ray analysis of chosen samples. Whenever necessary, the examination was complemented by microchemical tests. The research enabled the observation of changes introduced with the passage of time, such as the inclusion of new pigments. The result of the research was the identification of the complete colour spectrum with over 40 components, providing an overview of the palette utilized in theatre scenery painting from the second half of the18th century to the 1920s.

    更新日期:2020-01-11
  • Uric acid enzyme biosensor based on a screen-printed electrode coated with Prussian blue and modified with chitosan-graphene composite cryogel
    Microchem. J. (IF 3.206) Pub Date : 2020-01-10
    Ratchaneekorn Jirakunakorn; Suntisak Khumngern; Jittima Choosang; Panote Thavarungkul; Proespichaya Kanatharana; Apon Numnuam
    更新日期:2020-01-11
  • Photoluminescence imaging of modern paintings: there is plenty of information at the microsecond timescale
    Microchem. J. (IF 3.206) Pub Date : 2020-01-09
    Marta Ghirardello; Gianluca Valentini; Lucia Toniolo; Roberto Alberti; Michele Gironda; Daniela Comelli

    Luminescent emission from artworks is usually employed by conservators and restorers as a visual and quick method for assessing the presence of protective varnishes and restoration materials, as well to evaluate the painting conservation status. Besides these mere qualitative observations, the analysis of both spectral and temporal features of the optical emission from a painting can provide useful information about the pictorial materials employed by artists. In this work we propose Multi-spectral Time-gated Photoluminescence Imaging to differentiate between luminescent pigments, on the basis of their different emission spectra and lifetimes. We present the application of the approach on two modern paintings from Fondazione Maimeri Private Collection, on which we differently probe the fast-living emission from surface varnish and lake pigment and the long-living trap state emissions from different semiconductor pigments. With the aid of the time gated detection we record the trap state emission of semiconductor pigments, otherwise covered by the intense fluorescence of the organic compound. The method is complemented with Macro-XRF analysis, to confirm the nature of the identified inorganic pigments, as zinc white and cadmium yellow. The protocol represents a rapid, non-invasive and reliable way for assessing the identification of luminescent pigments and their spatial distribution.

    更新日期:2020-01-09
  • 更新日期:2020-01-09
  • A magnetic thermosensitive fluorescence imprinted polymer for selective detection of bovine hemoglobin
    Microchem. J. (IF 3.206) Pub Date : 2020-01-09
    Lei Cai; Zhaohui Zhang; Haimei Xiao; Shan Chen; Jilin Fu

    In this paper, a new type of magnetic thermosensitive fluorescence imprinted polymer was prepared for high selective identification of bovine hemoglobin with the magnetic carbon dots as the fluorescence source, poly(n-isopropylamide) and N, N-methylenebis acrylamide as the functional monomers and cross-linker, respectively. The magnetic thermosensitive fluorescence imprinted polymer was characterized by Fourier-transform infrared, fluorescence spectrometer, scanning electron microscope, transmission electron microscope and vibrating sample magnetometer in detail. The fluorescence of the magnetic thermosensitive fluorescence imprinted polymer was quenched linearly with bovine hemoglobin concentration in the range of 0.1- 9.0 μM with the detection limit of 48.0 nM. The imprinting factor was 2.3, which indicated excellent specificity of the magnetic thermosensitive fluorescence imprinted polymer toward bovine hemoglobin. With the advantage of the thermosensitivity, the elution efficiency of bovine hemoglobin could be significantly simplified and enhanced. In addition, the developed method was applied for selective identification of bovine hemoglobin in the real samples with the recoveries of 99.0%-104.7%. This proposed protocol provides a feasible and reliable strategy for preparation of the smart imprinted material with multiple stimulation responses.

    更新日期:2020-01-09
  • 更新日期:2020-01-09
  • Effects of Milling on the metals analysis of soil samples containing metallic residues
    Microchem. J. (IF 3.206) Pub Date : 2020-01-08
    Jay L. Clausen; Samuel A. Beal; T. Georgian; K.H. Gardner; T.A. Douglas; Ashley M. Mossell
    更新日期:2020-01-08
  • Nanoparticles: Synthesis, characteristics, and applications in analytical and other sciences
    Microchem. J. (IF 3.206) Pub Date : 2020-01-08
    Muhammad Sajid; Justyna Płotka-Wasylka

    Nanoparticles (NPs) are widely employed in different research areas, ranging from analytical chemistry and environmental science to medicine, the agriculture and pharmaceutical industry. This is mainly due to the unique characteristics of NPs and the novelty they introduce in such applications. In analytical chemistry, the role of NPs can differ depending on the nature of the steps involved in analytical process. NPs are probably most useful for detection, but sample preparation has also profited from them. For instance, NPs can advantageously replace conventional sorbents for solid-phase extraction. Moreover, NPs are being increasingly used as stationary phases in gas and liquid chromatography or electrochromatography. In this review, a brief summary on the classification, synthesis methods, and properties of NPs is given. Moreover, the examples of applications in different research area are shortly presented. However, the merits of this work are to present the use of NPs in analytical chemistry field.

    更新日期:2020-01-08
  • The use of micro carbon pencil lead electrode for sensitive HPLC-ED analysis of selected antipsychotic drugs
    Microchem. J. (IF 3.206) Pub Date : 2020-01-08
    Daniel Riman; Jan Rozsypal; Vladimir Halouzka; Jan Hrbac; David Jirovsky
    更新日期:2020-01-08
  • Assessment and bioaccumulation of arsenic and trace metals in two commercial fish species collected from three rivers of Côte d'Ivoire and health risks
    Microchem. J. (IF 3.206) Pub Date : 2020-01-08
    Ahbeauriet Ahmed Ouattara; Koffi Marcellin Yao; Kakou Charles Kinimo; Albert Trokourey

    Arsenic and trace metal (Cd, Cu, Pb and Zn) concentrations in the liver, kidneys, and muscles of two fish species (Chrysichthys nigrodigitatus and Sarotherodon melanotheron) collected from three rivers (Bandama, Comoé, and Bia) in Côte d'Ivoire were examined from July to November 2016. A total of 102 fishes were sampled and measured by atomic absorption spectroscopy. The concentrations in the Chrysichthys nigrodigitatus muscles ranged from 20.9 to 427, 0.00 to 243, 20.1 to 243, 35.6 to 359, and 409.1 to 2003 µg/kg wet weight for As, Cd, Pb, Cu, and Zn, respectively. As for Sarotherodon melanotheron tissue, the concentrations varied between 4.13 and 357, 0.00 and 14.9, 53.8 and 313, 27.7 and 241, and between 153.1 and 2540 µg/kg wet weight for As, Cd, Pb, Cu, and Zn, respectively. The bioaccumulation factor showed low values, indicating a low accumulation of the metals in these fish species. The data were below the international guidelines, and the estimated dietary intake data revealed that consumption of Chrysichthys nigrodigitatus and Sarotherodon melanotheron tissues may pose no human risks. However, the population frequently consuming fish of about 68.5 g/day from the Bandama, Comoé and Bia Rivers may be exposed chronically to arsenic pollution, based on the non-carcinogenic risks index with a target hazard quotient higher than 1.

    更新日期:2020-01-08
  • Au-Pt@Biomass Porous Carbon Composite modified electrode for Sensitive Electrochemical Detection of Baicalein
    Microchem. J. (IF 3.206) Pub Date : 2020-01-07
    Hui Cheng; Wenju Weng; Hui Xie; Juan Liu; Guiling Luo; Shaomei Huang; Wei Sun; Guangjiu Li

    A gold and platinum bimetal decorated biomass porous carbon ([email protected]) composite was synthesized by carbonization of oyster mushroom and solvothermal method, which was applied to the electrode modification and electrochemical detection of baicalein. The structural and elemental aspects of [email protected] were analyzed by X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and Raman spectrum. The [email protected] modified carbon ionic liquid electrode (CILE) was prepared as working electrode for the detection of baicalein. Baicalein exhibited a pair of redox peak on cyclic voltammograms with enhanced peak currents, which proved the positive effects of the composite including the high conductivity of biometal, the catalytic activity of noble metal and the large-surface of porous carbon with excellent adsorption ability. Under the optimal conditions the oxidation peak currents of baicalein were linear with the concentration in 0.48-2.0 μmol L−1 and 4.0-140.0 μmol L−1 via differential pulse voltammetry and the limit of detection was calculated as 0.010 μmol L−1. The modified electrode was successfully applied to the detection of baicalein content in drug and human urine samples. Meanwhile, the low cost and facile preparation of oyster mushroom based BPC made it become a potential substrate material for electrode modification.

    更新日期:2020-01-07
  • Re-evaluation and optimisation of dissolution methods for strontium isotope stratigraphy based on chemical leaching of carbonate certificated reference materials
    Microchem. J. (IF 3.206) Pub Date : 2020-01-07
    Youlian Li; Chaofeng Li; Jinghui Guo

    Strontium isotope stratigraphy (SIS) is widely used in geoscience as a chemo-stratigraphic tracer. In past SIS research, diverse sample dissolution methods have been developed and applied to bulk carbonate rocks to extract target Sr isotope signatures of primary carbonates, which are easily contaminated with Sr from extraneous phases. However, the accuracy of the various dissolution methods is debated because all carbonate materials in previous studies were collected directly from the field and did not undergo strict homogeneity examination before sample dissolution. To verify and evaluate the actual bias for carbonate in SIS research, in this study, we analysed a set of artificial carbonate mixed standard samples including carbonate certificate reference materials (CRMs) GBW03105a for limestone and JDo-1 for dolostone in addition to that for clay minerals, GBW03103. These samples were verified to be stable in their Sr concentrations and 87Sr/86Sr ratios and could be used as benchmarks to enable reasonable evaluation on the extraction method for carbonate materials. We conducted a subtle chemical leaching experiment with 12 steps on these samples after preleaching by ammonium acetate. Our results show that the acidic preleach is useful in diminishing the Sr contamination from the extraneous phases. Nevertheless, the Sr contamination from the clay mineral can not be completely removed by the chemical leaching method and it would be more substantial for carbonate samples with lower purity and relatively lower original 87Sr/86Sr. Our work suggests an optimised dissolution scheme for carbonate 87Sr/86Sr analysis: (1) an acidic preleach to dissolve about ∼60% of the sample, (2) a further dissolution of ∼20% of the sample to prepare for the 87Sr/86Sr analysis, (3) leaving at least 10% of the sample undissolved. A simplified dissolution protocol with advantage of rapid operational and relatively-high reliability was finally proposed for strontium isotope stratigraphy research, particularly for reconstruction of secular Sr isotope evolution curve.

    更新日期:2020-01-07
  • Sodium gluconate capped silver nanoparticles as a highly sensitive and selective colorimetric probe for the naked eye sensing of creatinine in human serum and urine
    Microchem. J. (IF 3.206) Pub Date : 2020-01-07
    Susan Sadeghi; Mohadeseh Hosseinpour

    A highly selective and fast analytical assay using sodium gluconate -capped Ag nanoparticles ([email protected]) was developed for the determination of creatinine by UV-Vis spectrophotometric detection. By adding creatinine to the [email protected] solution, the extinction intensity of the surface plasmon resonance (SPR) band of the corresponding UV-Vis spectrum at 393 nm reduced and meanwhile a new absorption peak appeared at 560 nm gradually with increasing creatinine concentratin. Induced aggregation of [email protected] by creatinine, accompanied with color changes from yellow to red can be directly observed by the nacked eye in five minutes. The extinction spectra ratio of A560/A393 was used for the colorimetric determination of creatinine. Effective parameters on the absorption intensity such as the sample pH, the type and buffer concentration, ionic strength and AgNPs concentration were optimized. Under the optimal conditions, a linear relationship between the SPR intensity ratio of A560/A393 values and creatinine concentrations is obtained over the range of 0.3-50 nM with a correlation coefficient of 0.9763 and a limit of detection of 0.2 nM. The relative standard deviation (RSD%) for five measurements of creatinine solution at 1 nM was 4.0%, exhibiting good repeatability. The results indicate that the developed probe can be successfully used for the determination of creatinine in serum and urine samples with satisfactory results.

    更新日期:2020-01-07
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